Dental obturator points are known (WO2006/082078). Dental obturator points are used by the dental practitioner in endodontic therapy to fill a prepared root canal. Given the small dimensions of the root canal and the fact that root canals are frequently not straight, but shaped with turns and screw-like portions, any obturator point used for dental purposes must provide a combination of high strength and flexibility.
Moreover, given that radio opacity of the dental obturator point is essential in subsequent diagnostic methods, obturator points are required to contain significant amounts of radio opaque material such as specific inorganic fillers.
Moreover, during retreatment of a dental root canal which had previously been filled with a dental obturator point, it is necessary to eliminate the dental obturator point completely from the dental root canal by using conventional dental instruments.
Moreover, dimensional stability of the dental obturator point is essential during storage given that dental obturator points are distributed in standardized sizes. Dimensional stability of the dental obturator point in the root canal is also important for the success of the root canal therapy.
Gutta percha is conventionally the predominant material used to obturate a root canal after it has undergone endodontic therapy. The physical and chemical properties of gutta percha, including inertness and biocompatibility, melting point, ductility and malleability, and excellent retreatment properties are the reason that dental obturator points are usually made of gutta percha filled with about 70 percent by weight of zinc oxide. However, the mechanical properties of the gutta percha obturation points are considered to be unsatisfactory.
U.S. Pat. No. 4,425,094 discloses an endodontic points comprising hydrophilic, polymeric compositions, which are swellable when placed into a prepared root canal. The hydrophilic, polymeric composition may be a hydrophilic, polymeric urethane. However, the mechanical properties of the endodontic points are still unsatisfactory.
U.S. Pat. No. 5,118,297 discloses a dental obturator point having an obturation body of a plastic material such as UDEL polysulfone MG-11 (AMOCO Performance Products, Ine) or Vectra VC-3 (Hoechst Celanese Corp.) optionally containing powdered tungsten as an inorganic particulate filler.
The dental obturator point of U.S. Pat. No. 5,118,297 is problematic in that the material suggested for the obturation body is excessively stiff. Moreover, the plastic material suggested cannot be readily eliminated from the dental root canal in case of a retreatment of the dental root canal.
WO-A 2008046557 discloses a dental obturator point having an obturation body of a material comprising (a) a polymer blend comprising (a1) 5 to 95 wt % based on the total amount of the polymer blend of a thermoplastic epoxide amine addition polymer, and (a2) 95 to 5 wt % based on the total blend of a high performance polymer; and (b) a particulate filler; whereby the obturation body has a radio opacity of at least 3 mm/mm Al. Although the obturator point of WO-A 2008046557 provides improved mechanical properties with regard to strength and flexibility, the properties of the obturator point with regard to a retreatment of a dental root canal still need improvement.
EP 1 911 433 discloses a dental obturator point comprising a polymer blend of a thermoplastic epoxide amine addition polymer and a high performance polymer, and a filler. Although the mechanical properties of the dental obturator point are excellent, a retreatment of a root canal treated with the dental obturator point is hardly possible, cf. Comparative Example 1.
It is therefore an object of the present invention to provide a dental obturator point having an obturation body with high strength, excellent flexibility, and high radio opacity, whereby the dental obturator point may be easily produced, while at the same time the dental obturator point may be readily eliminated from the dental root canal by using conventional dental instruments used for the treatment of a root canal.
Moreover, the dental obturator points should preferably fulfill the requirements of ISO 6877, especially with regard to the brittleness test and the required radio-opacity of at least 6 compared to 1 mm aluminium.